[PATCH 30/35] mm: Implement find_get_entries_range()
Jan Kara
jack at suse.cz
Thu Jun 1 02:32:40 PDT 2017
Implement a variant of find_get_entries() that stops iterating at
given index. Some callers want this, so let's provide the interface.
Also it makes the interface consistent with find_get_pages().
Signed-off-by: Jan Kara <jack at suse.cz>
---
include/linux/pagemap.h | 13 ++++++++++---
include/linux/pagevec.h | 12 ++++++++++--
mm/filemap.c | 32 ++++++++++++++++++++++++--------
mm/swap.c | 11 ++++++-----
4 files changed, 50 insertions(+), 18 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 283d191c18be..df128a56f44b 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -333,9 +333,16 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
-unsigned find_get_entries(struct address_space *mapping, pgoff_t *start,
- unsigned int nr_entries, struct page **entries,
- pgoff_t *indices);
+unsigned find_get_entries_range(struct address_space *mapping, pgoff_t *start,
+ pgoff_t end, unsigned int nr_entries,
+ struct page **entries, pgoff_t *indices);
+static inline unsigned find_get_entries(struct address_space *mapping,
+ pgoff_t *start, unsigned int nr_entries,
+ struct page **entries, pgoff_t *indices)
+{
+ return find_get_entries_range(mapping, start, (pgoff_t)-1, nr_entries,
+ entries, indices);
+}
unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
pgoff_t end, unsigned int nr_pages,
struct page **pages);
diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
index 3798c142338d..93308689d6a7 100644
--- a/include/linux/pagevec.h
+++ b/include/linux/pagevec.h
@@ -22,10 +22,18 @@ struct pagevec {
void __pagevec_release(struct pagevec *pvec);
void __pagevec_lru_add(struct pagevec *pvec);
-unsigned pagevec_lookup_entries(struct pagevec *pvec,
+unsigned pagevec_lookup_entries_range(struct pagevec *pvec,
+ struct address_space *mapping,
+ pgoff_t *start, pgoff_t end,
+ unsigned nr_entries, pgoff_t *indices);
+static inline unsigned pagevec_lookup_entries(struct pagevec *pvec,
struct address_space *mapping,
pgoff_t *start, unsigned nr_entries,
- pgoff_t *indices);
+ pgoff_t *indices)
+{
+ return pagevec_lookup_entries_range(pvec, mapping, start, (pgoff_t)-1,
+ nr_entries, indices);
+}
void pagevec_remove_exceptionals(struct pagevec *pvec);
unsigned pagevec_lookup_range(struct pagevec *pvec,
struct address_space *mapping,
diff --git a/mm/filemap.c b/mm/filemap.c
index de12b7355821..e55100459710 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1354,9 +1354,10 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
EXPORT_SYMBOL(pagecache_get_page);
/**
- * find_get_entries - gang pagecache lookup
+ * find_get_entries_range - gang pagecache lookup
* @mapping: The address_space to search
* @start: The starting page cache index
+ * @end: The final page cache index (inclusive)
* @nr_entries: The maximum number of entries
* @entries: Where the resulting entries are placed
* @indices: The cache indices corresponding to the entries in @entries
@@ -1376,9 +1377,9 @@ EXPORT_SYMBOL(pagecache_get_page);
* find_get_entries() returns the number of pages and shadow entries which were
* found. It also updates @start to index the next page for the traversal.
*/
-unsigned find_get_entries(struct address_space *mapping,
- pgoff_t *start, unsigned int nr_entries,
- struct page **entries, pgoff_t *indices)
+unsigned find_get_entries_range(struct address_space *mapping,
+ pgoff_t *start, pgoff_t end, unsigned int nr_entries,
+ struct page **entries, pgoff_t *indices)
{
void **slot;
unsigned int ret = 0;
@@ -1390,6 +1391,9 @@ unsigned find_get_entries(struct address_space *mapping,
rcu_read_lock();
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, *start) {
struct page *head, *page;
+
+ if (iter.index > end)
+ break;
repeat:
page = radix_tree_deref_slot(slot);
if (unlikely(!page))
@@ -1425,13 +1429,25 @@ unsigned find_get_entries(struct address_space *mapping,
export:
indices[ret] = iter.index;
entries[ret] = page;
- if (++ret == nr_entries)
- break;
+ if (++ret == nr_entries) {
+ *start = indices[ret - 1] + 1;
+ goto out;
+ }
}
+
+ /*
+ * We come here when there is no page beyond @end. We take care to not
+ * overflow the index @start as it confuses some of the callers. This
+ * breaks the iteration when there is page at index -1 but that is
+ * already broken anyway.
+ */
+ if (end == (pgoff_t)-1)
+ *start = (pgoff_t)-1;
+ else
+ *start = end + 1;
+out:
rcu_read_unlock();
- if (ret)
- *start = indices[ret - 1] + 1;
return ret;
}
diff --git a/mm/swap.c b/mm/swap.c
index 6ba3dab6e905..88c7eb4e97db 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -889,10 +889,11 @@ void __pagevec_lru_add(struct pagevec *pvec)
EXPORT_SYMBOL(__pagevec_lru_add);
/**
- * pagevec_lookup_entries - gang pagecache lookup
+ * pagevec_lookup_entries_range - gang pagecache lookup
* @pvec: Where the resulting entries are placed
* @mapping: The address_space to search
* @start: The starting entry index
+ * @end: The final entry index (inclusive)
* @nr_entries: The maximum number of entries
* @indices: The cache indices corresponding to the entries in @pvec
*
@@ -908,13 +909,13 @@ EXPORT_SYMBOL(__pagevec_lru_add);
* pagevec_lookup_entries() returns the number of entries which were
* found. It also updates @start to index the next page for the traversal.
*/
-unsigned pagevec_lookup_entries(struct pagevec *pvec,
+unsigned pagevec_lookup_entries_range(struct pagevec *pvec,
struct address_space *mapping,
- pgoff_t *start, unsigned nr_pages,
+ pgoff_t *start, pgoff_t end, unsigned nr_pages,
pgoff_t *indices)
{
- pvec->nr = find_get_entries(mapping, start, nr_pages,
- pvec->pages, indices);
+ pvec->nr = find_get_entries_range(mapping, start, end, nr_pages,
+ pvec->pages, indices);
return pagevec_count(pvec);
}
--
2.12.3
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